1. Field of the Invention
The invention relates to pet foods, such as, canine biscuits, rawhide chews and feline biscuits for controlling the malodorous breath of animals, such as, dogs and cats. The invention also relates to processes for preparing such pet foods. The invention further relates to processes of controlling malodorous breath of pets, such as, dogs and cats, chewing on and eating such biscuits or chewing on such rawhide.
2. Background Art
Numerous volatile compounds are present in the headspace of the oral cavity, but the most important, in terms of concentration of potency, are volatile sulfur compounds. These compounds are formed by the putrefaction of sulfur-containing proteinaceous substrates by predominately gram-negative microorganisms in the mouth, primarily on the tongue. Volatile sulfur compounds (VSC) found in the oral headspace of individuals examined by investigators were hydrogen sulfide, methyl mercaptan (methanethiol), dimethyl sulfide and dimethyl disulfide. Of these, the two most volatile (i.e., odorous) are hydrogen sulfide (H.sub.2 S) and methyl mercaptan (CH.sub.3 SH). These sulfur compounds are regarded as the principal contributors to breath malodor.
Zinc acetate is an ingredient of dietary supplements i.e., to 1 mg daily [The Condensed Chemical Dictionary, 10th Ed., (1981), page 1107]. Zinc gluconate is a known dietary supplement and food additive and is used in vitamin tablets [The Condensed Chemical Dictionary, ibid., page 1109]
Zinc carbonate is useful as a topical antiseptic [The Condensed Chemical Dictionary, ibid., page 1108].
There are several patent references which disclose certain types of animal foods which contain zinc compounds.
U.S. Pat. No. 2,760,866 (Nielsen) discloses a feeding ration product for farm animals which dissolves in the drinking water of the animal and through the medium of the drinking water furnishes the animal with its optimal amounts of supplementary minerals. The product contains large amounts of phosphates and comparatively small amounts of zinc sulfate and other sulfates.
U.S. Pat. No. 3,899,607 ((Miller et al.) and its divisional case U.S. Pat. No. 4,032,665 (Miller et al.) disclose the production of a simulated bone by extrusion of a dough composition into a "bone-like shape" under conditions of elevated temperature and pressure. While these patents make no mention of the effect of zinc salts on controlling mouth odor, they disclose the use of a whitish pigment, such as, titanium dioxide or zinc oxide as an optional ingredient for raising the whiteness of the product.
U.S. Pat. No. 3,997,675 (Eichelburg) discloses that the palatability of dry animal food is improved by coating it with yeast which includes either primary dried yeast or secondary yeasts. According to Eichelburg, secondary brewer's dried yeast analyzes typically as containing 38.7 ppm zinc.
U.S. Pat. No. 4,737,365 (Meyer) discloses dry blending zinc oxide and zinc carbonate with proteinaceous feeds for dairy cattle and beef cattle to protect the protein against rumen digestion. Milk production in dariy cattle and rate of weight gain in beef cattle, it is disclosed, can be increased in relation to protein intake.
There are several patent references which disclose oral compositions which contain zinc salts as breath control agents.
U.S. Pat. No. 4,138,477 (Gaffar) discloses compositions for preventing and controlling mouth odor which contains, as the essential agent, a zinc-polymer combination formed by the reaction or interaction of a zinc compound with an anionic polymer containing carboxylic, sulfonic and/or phosphoric acid radicals. In Table I, at column 2, zinc oxide per se is tested against a combination of zinc oxide plus a copolymer. Numerous examples of zinc compounds that may be employed in combination with the polymer are listed at column 4, lines 5 to 26. The composition is disclosed as inhibiting volatile sulfur compounds, such as, hydrogen sulfide, methyl mercaptan and dimethyl sulfide. The zinc-polymer combinations, it is taught, have very little of the astringent, metallic taste characteristic of zinc ions. The composition may be used in mouth washes, dental creams, sugarless pressed candy and chewing gum.
U.S. Pat. No. 4,289,754 (Dhabhar et al.) and U.S. Pat. No. 4,325,939 (Shah) disclose mouthwash compositions containing an alkali metal or ammonium zinc citrate which provides less astringency without loss of anti-odor properties. It is also disclosed that zinc chloride has been used in mouthwash compositions and recognized as posssessing anti-mouth odor properties in those compositions.
U.S. Pat. No. 4,289,755 (Dhabhar) discloses a mouthwash composition with acceptable astringency and without loss of anti-odor properties and improved compatability with fluoride ions. The mouthwash composition employs zinc citrate. It is also disclosed that zinc chloride has been recognized as possessing anti-mouth odor properties in mouthwash compositions.
U.S. Pat. No. 4,469,674 (Shah et al.) discloses oral compositions containing zinc salicylate, zinc lactate or zinc gluconate in combination in an ionic fluoride salt to eliminate volatile sulfur compounds from the breath. The compositions may be used in a mouthwash, toothpaste, chewing gum, or lozenge.
U.S. Pat. No. 4,689,214 (Niles et al.) discloses a composition to prevent breath odor which contains a salt which provides zinc ions and an ionone ketone terpene derivative. Zinc compounds which may be used are listed at column 2, lines 1 to 10. The composition may be in the form of a mouth spray, mouth rinse or toothpaste.
U.S. Pat. No. 4,814,163 (Barth) discloses that zinc compounds are generally known to have deodorizing properties as well as other properties desirable in oral hygiene. See the paragraph bridging columns 1 and 2. Barth discloses a non-cariogenic, long-lasting, slow-dissolving solid antitartar mouth deodorant having improved taste and extended mouth odor reduction and control of tartar formation comprising a zinc compound which provides zinc, an ionone ketone terpene derivative and a mint flavor. The ingredients include a gluconate salt and an acidic pH to aid in zinc solubilization, in a sugar-free carrier. Zinc salts which may be used are listed at column 3, lines 40 to 52.
Petrodex breath spray for dogs and cats is commercially distributed. The breath spray is contained in a pump-top dispenser. The breath spray is stated to act quickly to help neutralize/control offensive mouth odors and unpleasant tastes and to help control bacteria and promote healthy gums. The ingredients of the breath spray is stated to be deionized water, glycerine, xylitol, ascorbic acid, zinc gluconate, carboxymethyl cellulose, flavor, glucose oxidase and lysozyme.
Maxi/Guard Oral Cleansing Formula (as a spray) is commercially distributed for bad breath and odor control. It is stated to contain zinc ascorbate which helps control the by-products of harmful bacteria in the oral cavity and sulfur bearing amino acids which absorb malodorous substances in the mouth.
Canine Breath Freshener is commercially distributed for bad breath and odor control.
See also U.S. Pat. Nos. 2,527,686, 3,772,431, 3,888,976, 4,022,880, 4,082,841, 4,144,323, 4,152,418, 4,154,815, 4,260,635, 4,364,925, 4,339,432, 4,503,070, 4,618,601, 4,647,452, 4,664,906, 4,684,528, 4,758,439, 4,740,368, 4,784,861 and 4,871,532, and British Published Patent Application No. 2210264A.